Point-of-care testing (POCT), which is diagnostic testing performed on site, has the potential to improve healthcare and healthcare delivery. The motivation for POCT is to bring medical testing conveniently and immediately to the patient. Samples can be obtained and tested, and results are analyzed immediately at or near the location of the patient, thus enabling more rapid medical diagnostics and treatment. Early POCT research included the work of Clark and Lyons in the 1960s, which resulted in the “enzyme electrode”for glucose measurement using the enzyme glucose oxidase (GOD). This work was the first demonstration of a biosensor, as well as the first glucose monitor. More comprehensive portable POCT technology was developed in the early 1990s, with a portable simultaneous multiple analyte whole-blood analyzer for optical monitoring of chemical reactions at nine wavelengths. However, the most significant advance in POCT technology has been the emergence of modern consumer handheld devices, such as the smartphone, which enables POCT devices to be portable, and handheld instruments, such as lab-on-a-chip (LOC), leading to the proliferation of POCT, especially in resource-poor settings.